Wrench sockets,socket drives and similar couplers



Feb. 17, 1970 R. symunsfi EIAL I 3,49

wmsu cn socmms 50cm DRIVES Ann sIMIL' R cburm ins.

Filed Sept. 1-4, 1966 INVENTORS RAYMOND G. KNUDSEN JAMES W. PRICE GENEE. OLSON ATTORNEY United States Patent 3,495,485 WRENCH SOCKETS, SOCKETDRIVES AND SIMILAR COUPLERS Raymond G. Knudsen, James W. Price, and GeneE.

Olson, Kenosha, Wis., assignors to Snap-On Tools Corporation, Kenosha,Wis., a corporation of Delaware Filed Sept. 14, 1966, Ser. No. 589,153The portion of the term of the patent subsequent to Sept. 20, 1983, hasbeen disclaimed Int. Cl. B25b 13/06 U.S. Cl. 81-121 6 Claims ABSTRACT OFTHE DISCLOSURE The invention involves hexagon and double hexagon or thelike flank sockets or drives for corresponding standard fasteners whichimpart the torque turning load thereto to the sides or flanks ratherthan to the corners thereof, and to accomplish this with limitedlooseness for oscillatory play and maximum accessible registry betweenthe driving and driven elements, the angularity of the socket faces arewithin a limited plus or minus range of 144 degrees outside and 216degrees inside as a preferred angularity for minimum permissiblelooseness with suflicient clearance to facilitate registry between thedriver and driven elements. The geometric peripheral configuration ofthe flank engaging driver jaws alternate between concavities to providecomplete nut corner driving disengagement, and the centers of theconcavities alternating with the oppositely inclined flank jaws aresymmetrically indexed on substantially 15 degree radii emanating fromthe Wrench or driver socket axis.

This invention relates to socket drives and more particularly to wrenchsockets of the flank drive type effective to engage the sides ratherthan the corners of standard fasteners such as hexagon nuts withsubstantially improved torque transmission characteristics over standardhexagon and particularly double hexagon corner drives heretofore ingeneral use. This application is related to our copending applicationSer. No. 321,955 filed Nov. 6, 1963, which eventuated into LettersPatent No. 3,272,430 dated Sept. 20, 1966.

It contemplates more especially the improved hexagon and double hexagonflank socket or wrench jaw drives for standard fasteners such as hexagonnuts and the like which impart the torque transmission load to the sidesor flanks rather than to the corners thereof and accomplishing this withlimited looseness or oscillatory-type play necessary to a degree so thatregistry is possible between the socket or wrench drive and the nutfasteners.

With the teachings of the present invention, the angularity of theoppositely related nut flank engaging surfaces is within a range whichwill afford minimum practical looseness for registry with the fastenernuts and contact therewith near but not at the corners to insure propernut turning leverage and to avoid under all circumstances comerengagement. The elimination of nut corner engagement is absoluteirrespective of wrench surface engaging flanks by reason of interposingconcavities between each pair of opposing angular flank surfaces aroundthe circumference of the Wrench socket or open end jaw configuration.This improves torque transmission characteristics, greater stresswithstanding configurations result, and both the hexagon fastener nutdrivers and particularly the double hexagon type wrench drives thereforeare rendered more egective to turn greater torque tightening loadswithout increasing the present wall socket thicknesses nor limitingregistration accessibility between the drive sockets and the nutfasteners.

The trend has for many years been in the direction "ice of reducingwrench socket wall thicknesses of driving sockets and particularly indouble hexagon or socalled twelve-point sockets which agord a doublebite or nut registration in half the arc of movement in restricted orunaccessible locations in tightening and loosening nut fasteners. Thisis particularly important in the automobile industry by reason of thedesign of engines which are provided with many nut fasteners inrelatively inaccessible places so that tWelve-point wrench socket drivesand increasingly thinner wrench socket walls are requirements that poseproblems which are eifectively overcome with the specific teachings ofthe present invention.

It is generally known that because of these requirements and the use oftighter applied fasteners with the higher compression engines, the thinwall double hexagon or twelve-point wrench socket is vulnerable in thesharp corners. This is true even though wrench socket materials havebeen strengthened greatly in the last decade or more so that improvementmust now come in providing a more effective torque transmitting wrenchsocket design. This has been accomplished with the teachings of thepresent invention by utilizing a socket design having specific ranges ofangularly related nut flank engaging surfaces that constitute a completeside drive socket with curved recess receiving rather than sharp cornerengaging expedients to relieve the stress therein and increase theresistance to stress with improved torque transmitting characteristicsand longer life to both the wrench sockets or open end wrenchesincluding box socket wrenches and the nut fasteners turned therewith.

One object of the present invention is to provide an improved side drivewrench or wrench socket design for hexagon nut fasteners and the likewherein a limited angular relation is provided between opposedcontiguous driving surfaces for nut fastener flank surface engagement.

Another object is to provide a more effective side drive wrench socketdesign which will vastly improve the torque transmitting characteristicsof thin wall wrench sockets and particularly thin Wall wrench sockets ofthe twelvepoint or double hexagon type without sacrificing freedom ofregistration between the sockets and the fastener nuts.

Still another object is to provide a wrench socket or its complementalmale drive with a hexagon or double hexagon configuration that morefully sustains the nut sides rather than the nut corners to accomplishnut turning with increased torque loads and less stress withoutsacrificing freedom of registration between the sockets and the fastenernuts.

A further object is to provide an improved wrench socket drive designwhich imparts increased side torque transmission to the fasteners andtotally relieves the corner contact stresses in the socket so thatimproved torque transmitting characteristics result with lessdeformation to the reacting surfaces of both the fasteners and thewrench socket jaws or drives, and accomplishing this without too muchlooseness or play of the ratcheting type and with sufficient freedom ofregistration therebetween.

A still further object is to provide an improved hexagon or doublehexagon wrench socket drive that provides maximum side torquetransmitting surface engagement with complemental nuts or theircounterparts, and totally eliminates corner loads thereon, andaccomplishing this with oppositely angular contiguous jaw surfaces oflimited angularity having alternately interposed recesses for nut cornerstress relief, thereby avoiding fastener corner mutilation withincreased load capacity in nut turning.

Still a further object is to provide a wrench socket or a male drivecounterpart thereof having improved nut turning torque transmittingcharacteristics of maximum side drive and zero corner engagements withminimum ratchet-type looseness and sufficient freedom of registrationwith complemental nut fasteners so that longer service is possible forboth with improved load bearing limits.

Other objects and advantages will appear from the following descriptionof an illustrated embodiment of the present invention.

In the drawing: FIGURE 1 is a perspective view of a wrench socketembodiment of the present invention, parts thereof being broken away andshown in section to clarify the showing.

FIGURE 2 is a plan view of a Wrench socket embodying features of thepresent invention, the nut fastener being shown in dotted outline toillustrate the torque transmitting side drive characteristics thereof.

FIGURE 3 is an enlarged fragmentary plan view similar to FIGURE 2 andillustrating the side drive characteristics of the socket design withoutany corner engagement with the nut fastener.

The structure selected for illustration is not intended to serve as alimitation upon the scope or teachings of the invention, but is merelyillustrative thereof. There may be considerable variations andadaptations of all or part of the teachings depending upon the dictatesof commercial practice. The present invention is exemplified by a wrenchsocket preferably though not essentially provided with a reducedcylindrical base 11 having a polygonal axially positioned boretherethrough, 1n this instance a square-shaped bore 12 for receiving acorrespondingly shaped but slightly smaller drive shaft in registrytherewith for detachable association 111 the customary manner forimparting rotation thereto and the fastener in registry therewith.

The base 11 of the socket 10 merges in a somewhat enlarged cylindricalbody 13 that is broached to otherwise polygonally shaped from theopposite side or end 14 thereof to present a definite and precisepolygonal socket 15 to be presently described. The socket 15 usuallycommunicates with the drive bore 12 so that the chips resulting from thebroaching of the socket 15 will find their way through the bore 12. Inthe present embodiment, a socket 15 is provided for a hexagon nut and itaffords a double bite on the complemental fastener which is usually asingle hexagon in shape. This is made possible by the double hexagon ortwelve point broaching which is specially configurated to provide a sidedrive engagement relative to a hexagon nut that are most always used inengines and most other devices held assembled therewith.

The standard hexagon or double hexagon socket usually comprises a seriesof equidistantly and alternately disposed relatively inward and outwardcorners to correspond with and afford registry over fastener nut sizedtherefor, and in the case of a double hexagon socket the nut can befitted therein every thirty degrees or every thirty degree turn ratherthan the usual sixty degree are of rotation to afford a double bitethereon in half the arc of swing for greater accessibility in restrictedspaces or locations. These advantages are somewhat offset by thereduction in wall thickness due to double hexagon broachings with twicethe outer corners that reduce wall body thicknesses in the regionthereof. It is these corners that, for the most part, carry the turningor torque load imparted to the fastener nut of six corners and,therefore, the stress is the greatest at the Weakest regions around theperiphery of the wrench socket.

To overcome this decided disadvantage and weakness, the wrench socket 15and for that matter its counterpart in a male drive should such bedesired for recessed heads of screw fasteners and the like, is providedwith a series of equidistantly spaced inner corners 16, in this instancetwelve in number, which alternate with equidistantly spaced outer curvedflutes 17 that are substituted for the usual outer corners in standardtwelve-point sockets. The radial lines to the inner corners 16 and thealternate bisectors of the curved flutes 17 which intersect and convergeat the axial center of the socket 15, form fifteen degree angles (FIGURE3) between alternate adjacent peripheral formations 16-17.

In the preferred embodiment, the outside angles formed by the straightintersecting surfaces 18-19 which are oppositely angulated, in thisinstance outwardly for substantially 144 degrees and inwardly angulatedrelative to the axial direction of the socket for substantially 216degrees (FIGURE 3) to define the inner corners 16. The corners 16measure, in this instance, one hundred and forty-four (144) degrees andthese load bearing surfaces 18-19 constitute the side drive engagementsfor the fastener nuts sized to fit therebetween with the nut corners 20disposed within and free of the curved outside flutes 17 with a minimumof clearance therewith. Thus the fastener nut corners 20 and their loadbearing sides 21 (FIGURE 3) constitute the outline for the fastener nut22, and the turning moment is imparted to the straight side walls 21thereof by the wrench socket surfaces 18-19 in one direction of rotationand the wrench socket surfaces 19- 18 in the opposite direction ofrotation.

While the nut 22 and its wrench socket 15 are stationary and under noturning torque load, the nut corners 20 and the nut sides 21 are freefrom load stress. During the application of a turning moment by thewrench socket 15 to the fastener nut 22 in either direction, however,only the straight side surfaces 21 thereof are under a torque load asare the alternate converging socket sides 18-19 which are in thethickest region of the socket wall 13. In neither event, the corners 20of the fastener nuts 22 are stressed or load bearing and correspondinglythe curved flutes or concavities 17 which are in the thinnest regions ofthe wrench socket wall 13, are never under direct stress so that thetorque transmission for tightening or loosening the fastener nuts 22 arealways carried by the strongest load bearing portions of the wrenchsockets 10. This is highly advantageous in increasing the loadcapacities of given wrench sockets so shaped as well as to insure flankengagement with the sides rather than the corners of the fastener nut22. Corner mutilation of nuts 22 is entirely eliminated with this typeof socket or open-end jaw constructlon, and all these advantages accruewithout undue looseness nor restricted range of registry between thewrench socket 15 and fastener 22 When the angularity of the socket faces18-19 are Within the limited plus or minus range of 144 degrees outsideand 216 degrees inside as a preferred angularity to accomplish theseattributes with minimum looseness and a sufficient degree of reglstrywithin practical requirements, these being the guiding and controllingprescriptions for a satisfactory construction embodying the teachings ofthe present invention.

This is the converse of loading stres in conventional wrenches andwrench sockets of both the single hexagon and the double hexagonstandard design. In the latter especially there is the greatest load inthe corners Where the wall thickness is minimum and comparatively thinowing to the twelve-cornered configuration which eliminates considerablebody and, therefore, is substantially weakened and less able to sustainrepeated heavy loads over extended periods of time. With the teachingsof the present invention and design, the greatest torque sustaining loadis borne by the comparatively large side surfaces of both the wrenchsocket 15 and the fastener nut 22 in the thickest and strongest regionsof the socket 10 whose corners have curved flutes 17 to minimize stressand increase strength and provide a side drive through the straightsurfaces 18-19 that are in the thickest regions reinforced by the innercorners 16. The fastener nut corners 20 are not, therefore, the engagingabutments for the socket 10-15 so that the torque transmittingcharacteristics of the wrench socket 10 are substantially increasedwithout increasing the thickness of the socket wall 13 that inaccordance with the dictates of commercial practice are made as thin aspossible in order to render them more accessible in restricted nutlocations. This advantage accrues even though the flank engagingreaction between the socket and the fastener nut 22 occurs near ratherthan at the corners of the latter, since at any point away from the nutcorners there is sufficient fastener body to withstand mutilation andparticularly corner mutilation.

The curvature of the flutes 17 is not critical but should provideminimum clearance for the nut corners 20 so that maximum body isattained for the wrench socket 110 in the critical regions of the socketrecess thereof. The greatest advantage with the improved torquetransmitting characteristics are attained by transferring the turningmoment stresses to the inside surfaces 18-19 and interior corners 16where the wall thicknesses are the greatest rather than the least as instandard sockets, and the torque load is applied to the side surfaces18-19 of considerable expanse so that the unit area load is minimum andboth the wrench socket 10 and fastener nuts 22 are the strongest. In theregion of minimum strength and thickness which in standard wrenchsockets is at the outside corners, the improved wrench socket 10 isrelieved of all corner contact stress and strain by providing curvedflutes 17 that are non-load bearing at all times. The maximum advantageshave been attained with the teachings of the present invention withoutany increase in cost of material or production costs.

While the outside angularity (relative to the socket axis) between theoppositely inclined fastener flank engaging surfaces 1819 need not beprecisely limited within a matter of several degrees (more or less), ithas been found that with a specific outside angle of 144 degreestherebetween a very effective ratio exists between required loosenessand registry of fastener nut 22 and socket 15, although a range of 140to 150 degrees for said outside angle or angles is deemed tolerable andwithin substantial commercial considerations. Important too is the factthat these advantages can be experienced without changing the shape,sizes, or design of hexagon nutfasteners which have been standard for solong that it would be scarcely possible to expect any change therein,except for special situations and purposes which would not command anygeneral acceptance among nut manufacturers and distributors. For thatreason, it is imperative to improve the design and structure of thewrench sockets and tools utilized for nut turning to tighten as well asloosen such threaded fasteners.

Although we have illustrated and described a preferred embodiment of theinvention, it must be understood that our invention is capable ofconsiderable variation and modification without departing from thespirit of the invention. We, therefore, do not wish to be limited to theprecise details of construction set forth, but desire to avail ourselvesof such variations and modifications as come within the scope of theappended claims.

We claim:

1. A wrench or the like having a fastener nut engaging socket defined bya plurality of uniformly spaced peripherally and radiallydisposedprotuberances presenting angularly related straight engagingsurfaces extending for the depth of said socket to constitute a driveelement, said straight angularly related surfaces being complementallyand peripherally disposed at substantially 144 degrees outside obtuseangles to each other for free registry with a straight sided and sharpcornered geometric fastener when in axial alignment with thelongitudinal axis of the wrench socket to constitute a driven element,there being flank surface engagement between said angularly relatedstraight socket surfaces and the straight peripheral fastener surfacesfor the transmission of a torque load to said fastener by said Wrenchsocket with engagement away from the corners of the driven element.

2. A wrench defined in claim 1 wherein said nut engaging socket isperipherally closed and said angularly related straight surfaces areprovided in uniformly spaced relation in pairs relative to each otherand spaced with intermediate concavities for complete fastener cornerdisengaging reception during turning engagement between the driver anddriven elements.

3. A wrench defined in claim 2 wherein said conti uous oppositelydisposed-pairs of straight surfaces have an outside angle ofsubstantially 144 degree and an inside angle of substantially 216degrees relative to each other.

4. A wrench defined in claim 3 wherein said angularly related andoppositely disposed pairs of straight surfaces present sharp corners andthese are interrupted by circumferentially interposed concavities toaccommodate the corners of the geometric fasteners, and the bisectors ofsaid corners and concavities are on 15 degree radii spaced of the wrenchpocket axis.

5. A wrench defined in claim 4 wherein said oppositely disposed pairs ofstraight surfaces inwardly intersect and said circumferentially spacedconcavities extend outwardly to open toward the socket axis.

6. A wrench defined in claim 4 wherein the points of convergence of saidoppositely angulated straight surfaces and the radii of said concavitiesare disposed on uniformly and alternately spaced radii of said wrenchsocket.

References Cited UNITED STATES PATENTS 2,961,905 11/1960 Stumpf 811213,079,819 3/1963 Wing 81121 3,273,430 9/ 1966 Knudsen et al. 81121FOREIGN PATENTS 228,067 9/ 1959 Australia. 1,012,053 4/1952 France.

MILTON S. MEHR, Primary Examiner

